Silver complex diffusion transfer process



United States Patent 3,335,005 SILVER COMPLEX DIFFUSION TRANSFER PROCESS Louis Maria De Haes, Edegem, Belgium, assignor to Gevaert Photo-Producten N.V., Mortsel, Belgium, a Belgian company No Drawing. Filed Aug. 5, 1963, Ser. No. 300,100 Claims priority, application Netherlands, Apr. 13, 1961, 263,591; Aug. 3, 1962, 281,743 14 Claims. (Cl. 96-29) The present invention relates to an improved and more especially to a simplified silver complex diffusion transfer process.

The present application is a continuation-in-part of our application Ser. No. 187,437 filed Apr. 13, 1962.

According to the known silver salt diffusion transfer processes the principle of which is described in the British patent specifications 614,155 and 654,630 and in the German patent specification 887,733 a light-sensitive silver halide emulsion layer is image-wise exposed whereupon it is pressed in the presence of developer and a complexing agent for the silver halide into contact with a material containing an image-receiving layer comprising development nuclei for the unexposed and complexed silver halide.

In various patent specifications for instance in the German patent specification 1,055,953 and in the Belgian patent specification 536,672 there has been proposed to apply to the light-sensitive and/ or to the image-receiving layer an after layer but here too the developing nuclei are present in the image-receiving material.

Finally, it is known from the U8. patent specification 2,843,485 and from the Belgian patent specification 533,879 to use in the preparation of a diffusion transfer image .a light-sensitive material comprising an after layer containing development nuclei. Thus this after layer is the image-receiving layer and the image-receiving material is free from development nuclei.

It has now been found that, according to the silver complex diffusion transfer process images of very good quality can be obtained by contacting an image-wise exposed light-sensitive material comprising a silver halide emulsion layer and a top layer of a water-permeable colloid in the presence of a developing substance, a complexing agent for silver halide and a treating liquid comprising developing nuclei and/ or substances capable of forming such nuclei with an image-receiving material which is not specially pretreated with developing nuclei and by separating the both materials from each other. The top layer of a water-permeable colloid may be a top layer of a gelatin-free, water-permeable colloid and the complexing agent for silver halide may be present in the treating liquid. A suitable image-receiving material may be selected from the group consisting of paper, film, textile, ceramic, metal, etc.

, It has further been found that according to the silver complex diffusion transfer process images of very good quality can be obtained on an image-receiving material comprising a support and at least one auxiliary layer by wetting an image-wise exposed light-sensitive material, comprising a support and a light-sensitive silver halide emulsion layer coated with a layer wherein a diffusion transfer image can be formed, with treating liquid, pressing said light-sensitive material against said image-receiving material and then separating both materials, the layer wherein the diffusion transfer image can be formed and the top layer of the image-receiving material being chosen in such a way that, when separating the lightsensitive material from the image-receiving material, the layer wherein the diffusion transfer image can be formed is at least partially transferred to the image-receiving ma- Ice terial, wherein the development nuclei for the complexed silver halide or the substances which may form development nuclei are incorporated into the treating liquid.

It was not at all to be expected to obtain diffusion transfer images of good quality with a light-sensitive and an image-receiving material as described above without incorporating development nuclei either into the imagereceiving material or into the layer coated on the lightsensitive emulsion layer.

The fact that in the process according to the present invention the development nuclei are present in the treating liquid involves a considerable simplification of the manufacture of the light-sensitive and the image-receiving material.

In a process according to the present invention the image-wise exposed light-sensitive material can be passed through the treating liquid together with the image-receiving material or both materials can be wetted on one side with treating liquid and then brought into contact with each other for instance by pressing both materials together between two rubber rollers whereupon both materials are separated. The layer present on the light-sensitive silver halide emulsion layer comprising the positive image is transferred hereby at least partially to the imagereceiving material.

It is also possible to wet only the image-wise exposed light-sensitive material with treating liquid whereupon it is pressed against a non-wetted image-receiving material so that the positive print obtained is not wet any more but practically completely dry.

In all these cases it is generally possible, provided a good thickness is chosen for the layer present on the lightsensitive emulsion layer, appropriate binding agents such as polyacrylamide are used for said layer, appropriate substances are incorporated in said after layer such as substances modifying the cohesion in said layer, an appropriate transfer material is used etc., to obtain from a same image-wise exposed light-sensitive mate-rial several positive prints by pressing said light-sensitive material, after a first diffuson transfer image has been formed, several times against an image-receiving material either or not preceded by wetting with treating liquid or with water.

Finally it is also possible to bring both the imagereceiving material and the light-sensitive material into contact with each other while applying heat for instance by using heated plates or rollers for pressing said materials tOgether. In this way completely dry prints are immediately obtained. For more particulars about this proc- 655 there can be referred among others to the German Utility Model No. 1,794,536.

The image-receiving material for use in the process according to the present invention may consist of a support for instance of paper, film, textile, ceramics, metal etc. or may consist of such a support on which at least one layer is present, the top layer being of such a nature that the layer present on the light-sensitive silver halide emulsion layer is at least partially transferred thereto When'separ'ating the light-sensitive and image-receiving material which were brought into contact with each other;

Preferably the image-receiving material consists of a support coated for instance with a so-called baryta-coated layer having as binding agent a protein as gelatin or casein. In addition to barium sulfate still other pigments may be applied such as kaolin titanium dioxide and the protein binding agent may also be wholly or partially replaced by polymerisation products such as for instance copolymers of butadiene and styrene, poly(styrene), copolymers of vinyl chloride and vinylidene chloride, copolymers of vinyl alkyl ethers and maleic anhydride or by mixtures of said products. Into one or more layers of the image-receiving material substances may be incorporated which play a prominent part in the formation of the diffusion transfer image such as black-toning agents among others those described in British patent specification 561,875 and in Belgian patent specification 502,525, complexing agents for the silver halide such as sodium thiosulfate, developing substances, anti-yellowing agents, optical bleaching agents, alkalis, softening agents etc.

The light-sensitive material comprises a support for instance of paper coated with a light-sensitive silver halide emulsion layer and with a top layer mostly of a gelatin-free, water-permeable colloid. The top layer is of such a nature that a diffusion transfer image can be formed therein and that it can be transferred to the imagereceiving material in the way described above.

The emulsion composition is that of a conventionally used emulsion in the art of diffusion transfer. The emulsion composition is not critical provided its silver salt(s) is(are) capable of development and diffusion in the exposed and non-exposed areas respectively with the rapidly required in diffusion transfer processes. Silver chloride emulsions, which may contain silver bromide or silver iodide, and to which other ingredients have been added so as to impart the desired emulsion characteristics are referably used. The light-sensitive emulsion is usually applied in such a way that per sq. m. of light-sensitive material an amount of silver halide is present equivalent to from 0.2 to 2 g. of silver. Any such emulsion can be hardened or slightly hardened.

Appropriate binding agents for the layer coated on the light-sensitive silver halide emulsion layer are among others the following water-permeable colloids: methyl cellulose, the sodium salt of carboxy methyl cellulose, hydroxy ethyl cellulose, hydroxy ethyl starch, hydroXy propyl starch, sodium alginate, gum tragacanth, starch, poly(vinyl alcohol), poly(acrylic acid), poly(acry1 amide), poly(vinyl pyrrolidone), poly(oxyethylene), copoly(methyl vinyl ether/maleic acid), etc. The thickness of this after layer varies according to the nature of the colloid applied, the viscosity of the used colloid solution, the number (only one or several) of diffusion transfer copies which are intended to be made with the lightsensitive material, etc. This water-permeable layer is preferably not hardened.

Into the light-sensitive emulsion layer and/or into an adjacent water-permeable layer some substances may be incorporated for instance developing substances such as 3-pyrazolidone developers and hydroquinone, softening agents, black-toning agents and the like.

In the treating liquid a complexing agent for silver halide may be present, such as sodium thiosulfate, the amount being preferably comprised between 5 and 20 g. per litre of treating liquid, further still other substances playing a part in the diffusion transfer process may be incorporated such as alkalis, developing substances and black-toning agents such as those described in the above cited patent specifications.

In any event development nuclei for complexed silver halide and/or substances which may form development nuclei for instance by reaction with complexed silver halide are present in the treating liquid in amounts comprised between 0.01 and 1 g. per litre.

By development nuclei for complexed silver halide is understood nuclei for physical development as well as ingredients for chemical image formation.

Development nuclei for complexed silver halide which are suitable for being used in a process according to the present invention are sulfides, selenides, polysulfides, polyselenides, thioureas, mercaptanes, stannous halides, heavy metals or their salts and fogged silver halide. Sulfides of heavy metals such as of antimony, bismuth, cadmium, cobalt, lead, nickel and silver are also suited. Lead sulfide and zinc sulfide as well as the complex salts thereof are especially effective either in themselves or mixed with thio-acetamide, dithiobiuret and dithiooxamide. Among the heavy metals silver, gold, platinum, palladium and mercury arc to be mentionad, preferably in colloidal form. The noble metals among them are the most active.

It is very well possible to reduce the treating liquid to an alkaline suspension of development nuclei and even to a suspension of development nuclei by incorporating all other substances of importance for the formation of the diffusion transfer image into the light-sensitive and image-receiving material used.

For more particulars about exposure and developing apparatus which may be applied in a process according to the present invention as well as about the silver halide diffusion transfer process in general and the material of use in said process there can be referred to Progress in Photography, vol. I, 1940-1950, pages 76, 77 and 140; vol. II, 1951-1954, pages 156-7; vol. III, 1955-1958, pages 24-36 and to the patent literature cited therein.

The following examples illustrate the present invention.

Example 1 A light-sensitive material is prepared by coating a paper support of g./ sq. m. with a gelatino silver chloride emulsion as usual hardened with formaldehyde. This emulsion is coated in such a way that 1 g. of silver is present per sq. m. Hereupon an after layer of the sodium salt of carboxy methyl cellulose is applied in such a way that 0.5 g. is present per sq. In.

Then the light-sensitive material is image-wise exposed and passed through a developing solution in a developing apparatus for diffusion transfer together with a sheet of common paper which is used as image-receiving material and which is pressed against this light-sensitive material.

The developing solution has the following composition:

Water cm. 1000 Anhydrous sodium sulfide g 75 Sodium hydroxide g 10 Potassium bromide g 1 Hydroquinone g 16 1-phenyl-3-pyrazolidone g 1 Anhydrous sodium thiosulfate g 10 Colloidal silver g 0.2

After squeezing between the rubber rollers of the developing apparatus and after a contact time of about 10 see. both materials are separated. A positive print of the original is obtained.

Example 2 Example 1 is repeated adding, however, to the developing solution 0.05 g. of l-phenyl-S-mercapto-l,2,3,4-tetrazole. In this way a positive print is obtained having a more black image tone than that of Example 1.

Example 3 A light-sensitive material is prepared by coating 21 paper support of 90 g./sq. m. with a gelatino silver chloride emulsion which is hardened as usual with formaldehyde. This emulsion is coated in such a way that 1 g. of silver is present per sq. m. Hereupon an after layer is applied from the following solution:

Water cm. 1000 PAM 75 (trade name for a polyacrylamide marketed by American Cyanamid Company, New N.Y., U.S.A.) g 10 12.5% aqueous saponine cm. 5

This solution is coated in such a way that 0.5 g. of dry substance is present per sq. m. This light-sensitive material is image-wise exposed to an original and passed through the developing solution described in Example 1. This developed material is pressed against a dry sheet of common paper. After a short contact time both materials are separated. An excellent positive image of the original is obtained.

' Example4 The process of Example 3 is repeated, by using however a light sensitive material which instead of being coated over with a polyacrylamide layer is coated over with a top layer from the following solution in a proportion of 1 liter per 20 m Water cm. 1000 Hydroxyethyl starch having a substitution degree of 0.27 of hydroxyethyl groups g 40 10% aqueous saponine cm. l

'1 I Example 5 A light-sensitive material is manufactured by coating .onto a paper support of 90 g./sq. m. a silver chloride emulsion in such a way that 1.33 g. of silver chloride is .present'per sq. m. Then at 45 C. an after layer is applied to said silver halide layer from the following solu- 'tion:

Water cm. 1000 Pam 75 (trade-name) g 10% aqueous saponine cm. 10

The solution is coated onto the silver chloride layer in such a way that 1 litre covers 10 sq. In.

7 An image-receiving material is manufactured by coating at 45 C. a paper support of 90 g./sq. m. with the following composition:

Water cm. 30 0 Gelatin g 10 56% aqueous barium sulfate g 700 This composition is coated in such a way that 1 litre covers 40 sq. m. of paper support. 0

The light-sensitive material is now image-wise exposed and together with the image-receiving material passed through a ordinary diffusion transfer developing apparatus containing a solution of the following composition:

Then both materials are pressed together and separated. On the image-receiving material a positive copy of very good quality is obtained.

Example 6 A light-sensitive material as described in Example 5 is wetted after image-wise exposure at one side with the treating liquid of Example 5 containing, however, no sodium thiosulfate. This negative material is then pressed against a dry image-receiving material manufactured by coating at 45 C. a paper support of 90 g./sq. m. with the following composition:

Water cm. 300 Sodium thiosulfate-S-water g 100 Gelatin g 10 56% aqueous barium sulfate g 700 This composition was applied in such a way that 1 litre covers 40 sq. m. of support.

Both materials are separated and a nearly dry positive copy of the original is obtained.

6 Example 7 The process of Example 6 is repeated using:

(1) a light-sensitive material as described in Example 5,

(2) an image-receiving material manufactured as in Example 5 the coating composition containing, however, also 25 cm. of a 1% solution of l-phenyl-S-mercaptotetrazole in ethanol, and

(3) a treating liquid as in Example 5 containing, however,

no 1-phenyl-5-mercapto-tetrazole solution.

After obtaining a first positive copy, the light-sensitive material is once again wetted with treating liquid and pressed against a second dry image receiving material. In this way two positive copies of a same exposed light-sensitive material are obtained.

Example 8 A light-sensitive material as described in Example 5 is passed after image-wise exposure, together with an imagereceiving material manufactured as described below, through a treating liquid as described in Example 5 containing, however, no sodium thiosulfate and no l-phenyl- S-mercapto-tetrazole.

The image-receiving material used is manufactured by coating at 45 C. onto a paper-support of g./ sq. m. the following composition:

Water cm. 300 Sodium thiosulfate-S-water g 1% solution of 1-phenyl-5-mercapto-tetrazole in ethanol cm. 25 Gelatin g 10 56% aqueous barium sulfate g 700 The composition is applied in such a way that 1 litre covers 40 sq. m. of support.

When both materials leave the bath of treating liquid they are pressed together between a set of heated rollers whereupon they are separated. Immediately dry copies are obtained.

. Example 9 A light-sensitive material as described in Example 5, the after-layer of which is coated from the coating composition described in Example 5 but containing in addition thereto 10 cm. of a 1% solution of l-phenyl-S-mercaptotetrazole in ethanol, is wetted after image-Wise exposure with the treating liquid of Example 7. Then it is pressed against a dry image-receiving material as described in Example 5 and brought between heated plates. Immediately dry copies of good quality are obtained.

Example 0 The process described in Example 5 is repeated using, however, an image-receiving material manufactured by coating a paper support of 90 g./sq. m. with the following composition:

Water cm. 100 Kaolin g 60 Turkey-red oil cm. 10 Casein g 10 Ammonium hydroxide cm. 10

Said composition is applied in such a way that 1 litre covers 40 sq. m. of support.

Example 11 The process according to Example 10 is repeated using, however, in the manufacture of the image-receiving material the following composition:

Water cm. 100 Kaolin g 60 Turkey-red oil cm. 10 40% aqueous dispersion of copoly(ethylacrylate/ vinylisobutyl ether/ styrene/ acrylic acid) (66/ 20/ 12/2) cm. 20

Instead of wetting both the light-sensitive and the image-receiving material with treating liquid only the light-sensitive material is wetted therewith whereupon it is pressed against the dry image-receiving material.

Example 12 The process of Example 11 is repeated by using, however, a light-sensitive material which instead of being coated over with a polyacrylamide layer is coated over with a top layer from the following solution in a proportion of 1 litre per 20 sq. m.

Water cm. 1000 Hydroxyethyl starch having a substitution degree of 0.27 of hydroxyethyl groups g 40 aqueous saponine cm. 10

What I claim is:

1. A process for producing an image on an image-receiving material which comprises the steps of:

(1) exposing to a light image a light-sensitive material comprising a silver halide emulsion layer and an external water-permeable colloid layer, said colloid layer being adapted to have an image formed therein by diffusion of a complexed silver halide from said emulsion layer, said layer being further adapted to adhesively transfer at least a stratum thereof to said image-receiving material when the materials are brought into contact,

(2) in order to develop the light-sensitive material and produce the difiusion transfer image, wetting at least one member of the light-sensitive material and the image-receiving material with an aqueous processing liquid containing development nuclei or nuclei-em gendering substance for promoting reduction to metallic silver of said diifused silver halide and being at least substantially free of film-forming material, and pressing the wetted material while still moist and the other material together in the presence of a developing agent and a complexing agent for silver halide, and

(3) separating the light sensitive material from the image-receiving material to cause a physical transfer of at least a stratum of said colloid layer with the diffusion transfer silver image formed therein from said light-sensitive material to said image-receiving material.

2. The process of claim 1 wherein said external colloid layer is free of gelatin.

3. The process of claim 1 wherein said steps (2) and 3) are repeated to produce a plurality of copies.

4. The process of claim 1 wherein said treating liquid is applied to said light-sensitive material alone.

5. The process of claim 1 wherein heat is applied while said materials are pressed together.

6. The process of claim 1 wherein said emulsion layer is at least slightly hardened.

7. The process of claim 1 wherein said external colloid layer is unhardened.

8. The process of claim 1 wherein said complexing agent is carried by said image-receiving material.

9. The process of claim 1 wherein said developing agent and said complexing agent are contained in said treating bath.

10. The process of claim 1 wherein said developing agent is incorporated into said light-sensitive material. I

11. The process of claim 1 wherein said treating liquid is an aqueous solution.

12. The process of claim 1 wherein said image-receiving material comprises a paper support and a layer containing a binding agent comprised essentially of a protein or a synthetic polymer.

13. The process of claim 12 wherein said layer also contains a pigment.

14. The process of claim 13 wherein said pigment is barium sulfate or China clay.

References Cited UNITED STATES PATENTS 2,653,527 9/1953 Land 96-29 2,662,822 12/1953 Land 9629 2,843,485 7/1958 Yutzy et al. 9628 2,992,936 7/1961 Rowland 117152 3,067,033 12/1962 Weyde 9628 NORMAN G. TORCHIN, Primary Examiner. J. TRAVIS BROWN, Examiner. 

1. A PROCESS FOR PRODUCING AN IMAGE ON AN IMAGE-RECEIVING MATERIAL WHICH COMPRISES THE STEPS OF: (1) EXPOSING TO A LIGHT IMAGE A LIGHT-SENSITIVE MATERIAL COMPRISING A SILVER HALIDE EMULSION LAYER AND AN EXTERNAL WATER-PERMEABLE COLLOID LAYER, SAID COLLOID LAYER BEING ADAPTED TO HAVE AN IMAGE FORMED THEREIN BY DIFFUSION OF A COMPLEXED SILVER HALIDE FROM SAID EMULSION LAYER, SAID LAYER BEING FURTHER ADAPTED TO ADHESIVELY TRANSFER AT LEAST A STRATUM THEREOF TO SAID IMAGE-RECEIVING MATERIAL WHEN THE MATERIALS ARE BROUGHT INTO CONTACT, (2) IN ORDER TO DEVELOP THE LIGHT SENSITIVE MATERIAL AND PRODUCE THE DIFFUSION TRANSFER IMAGE, WETTING AT LEAST ONE MEMBER OF THE LIGHT-SENSITIVE MATERIAL AND THE IMAGE-RECEIVING MATERIAL WITH AN AQUEOUS PROCESSING LIQUID CONTAINING DEVELOPMENT NUCLEI OR NUCLEI-ENGENDERING SUBSTANCE FOR PROMOTING REDUCTION TO METALLIC SILVER OF SAID DIFFUSED SILVER HALIDE AND BEING AT LEAST SUBSTANTIALLY FREE OF FILM-FORMONG MATERIAL, AND PRESSING THE WETTED MATERIAL WHILE STILL MOIST AND THE OTHER MATERIAL TOGETHER IN THE PRESENCE OF A DEVELOPING AGENT AND A COMPLEXING AGENT FOR SILVER HALIDE, AND (3) SEPARATING THE LIGHT SENSITIVE MATERIAL FROM THE IMAGE-RECEIVING MATERIAL TO CAUSE A PHYSICAL TRANSFER OF AT LEAST A STRATUM OF SAID COLLOID LAYER WITH THE DIFFUSION TRANSFER SILVER IMAGE FORMED THEREIN FROM SAID LIGHT-SENSITIVE MATERIAL TO SAID IMAGE-RECEIVING MATERIAL. 